Fix and Fit
Soldering...In The Dispensary - Part Two
By Alex Yoho, ABOM

In the last Fix & Fit, we determined what was needed to make the investment in time, space, and money worthwhile for soldering. Now we are ready to get to work.

There are two ways to heat metal for the purpose of soldering a frame: Torch welding and electric resistance. Using either, remember that the frame itself is heated to melt the solder, not the solder to melt onto the frame. If a torch melts the solder before the frame is hot enough, it just beads up and does not stick.

The amount of heat that is applied to a frame is important. For most metals, the frame is not heated to a bright red-hot, which causes the frame to blacken with oxidation, and solder will not stick. Concentrate the heat in the area to be repaired, and when you see a dull red glow, regulate the heat.

With the frame clamped, heat the frame and apply the solder. Allow to sweat together

SWEAT THE SMALL STUFF

The next step is to "sweat" the pieces together. Clipped solder is done in this manner: Place a piece of solder on the fluxed area to be repaired, then sandwich it with the replacement part, and keep the pieces from moving as heating.

Using a thicker, stickier flux will sometimes aid in keeping things from sliding around. Flux cleans the metal and the solder will flow wherever the metal is clean and hot. If you use too much, the solder will follow the flux run and flow away from the joint. Remember to heat the frame from behind the solder, and never heat the solder itself.

If you are using flux-filled tube solder, heat one piece of the frame and, when hot, touch the stick of solder to it. If the solder doesn't melt immediately, pull it away, continue to heat for a second, and try again. For most joints, you will use about two millimeters of solder.

Next, hold the two pieces together and sweat them together. There should be enough residual flux to clean the opposite piece; but if the solder won't flow, you may repeat this on the other side so that both sides will have solder and flux. It's easy to use too much solder this way, so just use a touch on the second piece.

If the joint is in a difficult area, it is sometimes advisable to heat the heavier piece until it barely melts the solder. Then heat the smaller piece and put a little flux on it. Heat the heavier piece again, and as you observe the solder beginning to flow, introduce the smaller piece. If you are using a torch, you can move the flame to heat both pieces. This technique works well for welding a hinge to an endpiece.

When there is little surface area to connect, put the solder first on the smaller piece, such as when soldering a nose pad arm to an eyewire. If you put solder on the larger eyewire, it flattens out on the surface, and not as much sticks to the pad arm when it is introduced.

Don't forget that when you solder, temperatures reach around 1,200 degrees. Use soldering jigs, hemostatic pliers, and probes to protect fingers.

When you have finished soldering the frame, wait about 10 seconds--allowing the frame to cool slowly--then plunge all hot pieces into a container of water. If you plunge the frame into the water immediately, it "quenches" the metal and thus removes its temper.

If a temple is hard to bend, remove the temple tip and heat the core to red-hot. Quench it quickly in cool water, and it will bend like butter. This is great for temple ends, but for parts of a frame that need to hold adjustments, it's better to wait just a bit to preserve the metal's resistance to bend.

	After the repair work is complete, the frame can be buffed to a brilliant shine

CLEAN UP

Now comes the time when you need to decide how well you want to clean the frame. Even if you don't want the joint to look good, clean off the oxidation and any burnt-looking paint with rubber-bonded abrasive, sandpaper, or a wire or fiberglass brush pencil. All of these will leave a clean brushed or patina finish which blends in fine with a gunmetal finish.

To move beyond a rough cleaning, you will need a buffing lathe. The buff is first charged with rouge by pressing the rouge bar against the spinning buff. Holding the frame firmly, touch it lightly to the spinning buff just below the center on the front face. Always keep the frame moving, continuing until the area has a bright luster.

Use extreme caution: The buff could grab the frame and wrap it into a worthless ball of wire, or it might even wrap painfully around your fingers.

After buffing, you will usually have a shiny white metal. If the frame is gold or some other color metal, electro-
plating--electrochemical deposition of a certain metal element on a base metal--is necessary.

Before the actual plating, you will need to clean the frame in a manner that will accept it. There should be no visible trace of oxidation or other dirt and grease. Beyond visible inspection, you can tell if the surface is ready by observing the sheeting of water as you rinse it. If grease or oil is still on the frame, it will bead up or break the water sheet. Ultrasonic cleaners work well for this purpose, but there are chemical degreasers for each type of plating. There are two different plating methods.

Chemical bath. A vat or beaker holds the chemical bath and the anode, a piece of the pure metal to be deposited on the base metal. Direct current (DC)--the type from a battery or rectifier, not an outlet--electricity is connected to the anode and the piece to be plated, which is swished gently back and forth in the bath. This takes from a few seconds to a few minutes. The thing that makes this undesirable is the large amounts of hazardous chemicals that are used, including cyanide-based baths and acid baths. There are chemicals available that are cyanide-free, but they still contain strong acids or bases.

Pen plating. These units pass electricity through a felt-tip marker that contains the anode and hazardous chemicals. They use low voltage electricity from a rectifier or battery. All the chemicals are inside the pen except what is "drawn" on the metal; and the plating can be localized for two-toned finishes. This makes the pen-type plating setup a good choice for occasional soldering and special applications in a large volume business.

Although electroplating deposits metal on metal, it will not fill in scratches or pits, nor will it make a dull finish shiny. Sanding and buffing are the way to get rid of these problems, which are normally caused by acidic perspiration. Heavy plating will retard this process significantly, but it may be necessary to put some clear lacquer on in addition.

In the next Fit & Fit, we'll discuss methods of finishing frames.